Non-destructive testing does not interfere with or affect the properties of the detected objects, does not harm the objects provided for testing the tissues, and uses the reactions or chemical methods caused by physical changes such as abnormal internal structure or defect heat, sound, light, electricity and magnetism as the states, properties and quantities of using modern technology and equipment, sample surface and internal structure, properties and defect types. Examination and test methods for shape, location, size, distribution and change [1]. Nondestructive testing is an effective tool for industrial development. To some extent, it reflects the level of industrial development of a country. The importance of nondestructive testing has been recognized. There are four kinds of nondestructive testing, namely, RT, UT, MT and PT. There are other NDT methods such as eddy current detection (ECT), acoustic emission detection (AE), thermal imaging/infrared (TIR), leakage detection (LT), AC field measurement technology (ACFMT), magnetic flux leakage detection (MFL), far field testing (RFT), ultrasonic Time-of-flight diffraction (TOFD), etc.


Nondestructive testing is to use the characteristics of sound material, optics, magnetics and electricity to detect the defect or non-uniformity of the test object without impairing or affecting the performance of the test object. Given the size of the defect, the nature and quantity of the location information are given. Compared with destructive testing, nondestructive testing has the following characteristics.  The first is non-destructive, because it is completed without impairing the performance of the test by using the test object; the second is comprehensive, because the test is non-destructive, it can detect 100% of the total test object, which is impossible to destructive detection if necessary; the third is complete destructive detection which is usually only applicable to raw material testing, such as tension and pressure. Mechanical engineering, such as shrinkage, bending, etc., is used for nondestructive testing of raw materials, finished products and supplies. Unless the service is not ready to continue, it is not destructive testing and non-destructive testing, and will not damage the object to be tested because of its performance. Therefore, it is not only the raw material for each intermediate step of manufacturing process, until the final product is used for the whole test, but also for the service in the test device.


NDT visual inspection: 1. Weld surface defect inspection. Check weld surface cracks, incomplete penetration and weld leakage welding quality. 2. National Examination. Check surface cracks, spalling, cable, scratches, dents, protrusions, spots, corrosion and other defects. 3. Examination of cavity. When some products (such as worm pump, engine, etc.) work, remote visual inspection will be carried out according to the technical requirements of the project. 4. Assembly inspection.  If necessary, use the same three-dimensional industrial video endoscope component quality inspection when needed; or after the assembly process, check whether the assembly position of parts and components meets the drawings or technical requirements; and the existence of assembly defects. 5. Additional material inspection. Check for residual dust, foreign bodies and other residues in the lumen.